Flush floor mounted safety latch for hydraulic lifts



Aug 26, 1958 l. v. K. HOTT ETAL 2,849,084

FLUSH FLOOR MOUNTED SAFETY LATCH FOR HYDRAULIC LIFTS 2 Sheets-Sheet 1Filed Sept. 9, 1954 Aug. 26, 1958 l. v. K. HOTT ET AL 2,849,084

FLUSH FLOOR MOUNTED SAFETY LATCH FOR HYDRAULIC LIFTS 2 Sheets-Sheet 2Filed Sept. 9. 1954 .Am n

FLUSH FLOOR MOUNTED SAFETY LATCH FOR HYDRAULIC LIFTS Ion K. Hott andDavid M. Goldzwig, Dayton, Ohio, asslgnors to The Joyce-CridlandCompany, Dayton, Ohio, a corporation of Ohio Application September 9,1954, Serial No. 454,890 3 Claims. (Cl. IS7-8.5)

The present invention relates to flush iioor `mounted safety latches forhydraulic lifts and more particularly to a safety device theeffectiveness of which is increased by the weight of the load upon it,although not necessarily so limited.

An object of the invention is the provision of a safety latch forhydraulic lifts which is strong .and sturdy and one which is simple inconstruction, easy and economical to manufacture, easy to operate andwhich is substantially fool-proof.

A further object of the invention is the provision of a safety devicefor a hydraulic device which remains in operation, allowing only travelin one direction until released.

A further object of the device is the provision of a safety latch for ahydraulic lift which is foot actuated,

and so placed and operated that it cannot be accidentally tripped.

A further object of the invention is the provision of a `safety latchwhich can be applied to a hydraulic lift for servicing all makes of carswith no other mechanical adjustments.

A further object of the invention is the provision of a safety latch fora hydraulic lift, all parts of which are substantially at or below floorlevel.

A further object of the invention is the provision of a safety latchwhich functions automatically at all times when the lift is in raisedposition, which has to be manually disengaged and which recocksautomatically.

Other objects and advantages reside in the construction of parts, thecombination thereof and the mode of operation, as will become moreapparent from the following description.

In the drawings, Figure l is a perspective view of one form of latchshowing a portion of iioor broken away and showing concealed portions indotted lines.

Figure 2 is a fragmentary vertical cross section taken substantially onthe line 2 2 of Figure l, showing the latch in operative position.

Figure 3 is a fragmentary vertical cross section showing the latch inits tripped position.

Figure 4 is a perspective View similar to Figure l showing a modifiedform of latch.

Figure 5 is a fragmentary vertical cross sectional view, takensubstantially on the line 5-5 of Figure 4.

Figure 6 is a fragmentary view of the device of Figure 4 partly in crosssection and showing the parts in tripped and inoperative position.

Figure 7 is an exploded view of the pawl or detent member and the weightassociated therewith.

Referring more in detail to the drawings, a pair of vert ticallydisposed cylinders or supporting members 10 and 11 are set in a concreteor other oor 12 and extend throughout their entire length below the oor.A channel member 14 is positioned at the lower ends of members 10 and11. The lower ends of these members 10 and 11 fit within the channel andthe member 14 operates as a locating and aligning element.

atent l 2,849,084 Patented Aug. 26, 1958 ICC The upper ends of thecylinders or support members 10 and 11 are provided with packing glands16 which are flush with the floor. Sliding within the cylinder members10 and 11 are a pair of cylindrical lifting elements or pistons 18.These elements are propelled upwardly by a hydraulically operated means(not shown). The lifting members 18 are provided at their upper endswith a pair of horizontally disposed frame engaging members or rails 20,disposed in parallel relationship, the distance between them being suchthat the members 20 are in a proper position to Contact the frame of anauto-mobile. The preceding device is conventional in hydraulic lifts andhas been shown merely for the purpose of illustration. The arrangementof this mechanism and the construction thereof may be varied dependingupon the particular requirements and the available parts.

A housing box 22 is set in concrete at flush floor level and is providedwith a pair of openings 24 and 26 located in alignment in its top andbottom walls. A pair of stationary cylindrical housing members 2S and 29are located under the floor and may be secured at intervals if desiredto the members 1i) and 11 respectively. The housing boxes 22 and 23 aresecured to the members 28 and 29 respectively. The structure isduplicated in the members 11 and 29. Slidable Within the cylindricalmember 28 and through the openings 24 and 26 is a rack member 30,provided on its exterior surface with a `series of wedgeshaped teeth 32.

A shaft 34 is journalled in opposite vertical walls of the housingmember 22, and carries a pinion member 36 provided with teeth 38. Theteeth 38 of the pinion 3 6 mesh with the teeth 32 of the rack member 30.The shaft member 34 is journalled in one Vertical wall 37 and extendsthrough the opposite wall of the housing 22 and extends further to thehousing 23. The housing 23 is attached to the other cylindricalvsupporting member 1l. The racks 30 are xedly attached to the frameengaging members 20, so as to be raised and lowered therewith.

The housing 22 contains pinions 36, not shown. The

pinions 36 operate in unison as a pair, moving concomitantly to keep theupper travel of theracks 30 synchronous and to keep the members 20 atthe same level in all positions of their upward and downward movement.This device may be called an equalizer.

The safety latch is housed within the box member 22. A pivot or fulcrumrod 42 is journalled in the vertically opposite walls of the box.Rigidly connected to the shaft 42 is a detent or pawl 44 and acounterweight member 46. The detent 44 and the counterweight member 46are joined by a portion 49, that is, the detent 44 and the counterweghtmember 46 are integral. The` `combined weight of members 44 46 may swingthrough dead center. When on one side of dead center the weight 46 urgesthe detent into engagement with the rack 30 and when on the other sideof dead center the combined weights of members 4.4 and 46 hold thedetent out of engagement with the rack. The detent is provided with atooth 48. The tooth 48 is provided with upper and lower surfaces sopitched as to mesh within the space or notch between two consecutiveteeth 32. The upper surface 48a of the tooth 48 has the same angle asthe slope of the underside of a tooth 32. The underside 48b of the tooth48 has an angle that is steeper than the slope of the upper side of atooth 32. Upward movement of the rack is allowed and downward movementprevented. The rack may move upwardly by stages, and rest at any pointWith out slipping back. The weight member 46 has an integral arm 50, sopositioned that the counterweight 46 and the arm 50 are on oppositesides of the fulcrum rod 42. A foot pedal or operating arm 52 is mountedon a pivot or fulcrum rod 54 and is provided with an arm 56. The members52 and 56 are positioned on opposite sides of the fulcrum rod 54 and thearm 56 is adapted to engage and actuate the arm 50. When the foot pedal52 is operated upwardly, the arm S6 will rock against the arm 50 causingthe weight 46 to swing in a counterclockwise direction, as viewed-inFigure 2, through dead center into the position shown in Figure 3. Asthe counterweight 46 isswung, the shaft 42 on which it is rigidlyconnected is rotated and the detent 44 is rocked in a counterclockwisedirection as shown in Figure 2 intothe position shown-in Figure 3,andtthetooth 48 is disengagedfrom the teeth 32 of the rack 30. When' thefoot pedal is lowered so as to be liush with the oor, the arm 56 willthen rock into engagement'with the main body of the weight 46 to actuatethe weight 46 and the pawl 44 through dead center, lto thereby cause the-pawl to drop into engagement with a tooth'32.

In operation, when the foot pedal 52is pressed downwardly, the tooth 48is engaged with the teeth of the rack 30. The weight 46 is in theposition shownin Figure 2. The foot pedal 52 is positioned so that aspace remains between it andthe wall-of the housing 22 so that the toeof an operator may-be inserted underneath it to operate it upwardly.When this is done, the parts assume the positions shown `in Figure 3.The detent 44 is out of engagement with the teeth 32and thereisnothingto prevent the downward; movement of the rack 30. As long as thepartsare in the position shown in Figure 2 with the ldetent 44 in engagementwith a tooth of the rack 30, the

force of the counterweight 46 and the shape of thev tooth 48 togetherwith the cooperating portion of the teeth 32 hold the tooth in itsengagement. The force ofthe weight of a car willreactwith the slantingengaging upper surfaces of the teeth 48 and 32 to further reinforce theengagement of the detent 44 by the teeth 32. It will thus be seen thatthe weight of a car reinforces the safety factor of the latch andincreases its effective engagement.

The upper surface of the foot pedal 52 is substantially flush with thefloor level and its accidental tripping is precluded.

The device is extremely sturdyand of such simple construction that itsmanufacture is inexpensive and yet the arrangement of parts is such thatthe device is practically fool-proof.

In the device shown in Figure 1, a pair of lifting members 18 are shown.In the modification shown in Figures 4 to 6, a single cylindricalelement 60 is mounted on a standard 62 and a single lifting element 64is shown. The upper end of the lifting element 64 carries an H-shapedmember 66, the two rails '68' of which constitute the automobile frameengaging elements. A rack member 70 is secured at its upper end to theH-shaped member and eX- tends through the casing 72 and into the tubularmember 73.

The cylindrical member 60 reaches to floor level and in this area isprovided with a latch housing 72. The rack member 70 is provided with avertically disposed series of aligned openings 74. The lower portion ofthe housing 72 is provided with a lower opening 76, into which openingthe tubular member 73 projects. A shaft 78 carries a detent 80 and aweight member 82, both Vrigidly connected to it. A shaft 84 carries atoe pedal or lever 86 and a rocking arm 88. All of this latch mechanismis `similar to that shown in Figures 1, 2 and 3, with the 4 exception ofthe rack member 70, which is provided with openings 74 in place of theteeth 32. As clearly seen in Figure 6, the safety latch recocksautomatically whenever member 66 is lowered to rest on the oor. A tooth90 on the detent 80 engages in the opening 74 of the rack.

Although therpreferred embodiment of the device has been described, itwill be understood that within the purview of this invention variouschanges may be made in the form, details, proportion and larrangement ofparts, the combination thereof Aand mode of operation, which generallystated consist in audevice capablev of carrying out the Objects s etforth, as disclosed and defined in the appended claims.

Having thus described our invention, we claim:

l. A safety device for a vehicle lift having means for raising a vehiclefrom a oor, said lift having a member provided with indentations. movingwithV the lift, including the combination 4of a pawhmechanism having anopperative position. and an inoperative position, said pawl mechanismpassing through dead ycenter when moving from one position to the other,means for mountingqthe pawl mechanism below floor level so as toengagethe indentations when inoperativeposition, andfoot operated meanslocated on the oor `level when the pawl mechanism is in voperativeposition .and positionedv below a portion of said vehicle raising means,said footoperated means engagingsaid pawl mechanism toactuatefthe same,said .footoperated means being vmovableinto a position above oor levelto actuate the pawl-mechanism from operative position into inoperativeposition, saidportion of said vehicle raising means when lowered to thefloor actuating the Afoot lmeans intofloor level position to therebyrecock the safety device.

2. A safety device according to claim l, wherein the floor is providedwitha Icavity in-.which thefoot operated means is, mounted, said cavity`providing a clearance whereby the foot voperated means may be raised'by the sole of a shoe.

3. A safety device according to claim 1, wherein the foot operated meansincludes-aPCdal member normally located flush with the floor,pivot'means `for mounting said pedal. member, and an arm directeddownwardly from the pedalmember.andintegraltherewitm said arm engagingan extension ofthepawlmeehanism to lactuate the pawl mechanismoutofcontactwith theindentations when the pedal member is movedoutof floorflush position, said. arm. engaging aportion, of the, pawl, mechanism tolswing the pawl mechanism. through dead center' into operative positionwhen the pedal member is returned to Hush-position.

References Cited-inthe le of thispatent UNITED STATES PATENTS 764,141Miller July 5, 1904 1,584,013 Collins Mayr l1, 1926 1,984,517 BurnettDec. 18, 1934 1,993,447 Hott yMar. 5, 1935 2,201,189 Makaroff et al.--.May 21, 1940 2,593,630 Thompson Apr. 22, 1952 2,608,381 Pelouch Aug.26, 1952

